Re: [boost] [type_traits] Time to upgrade to "version 2" ?

Subject: Re: [boost] [type_traits] Time to upgrade to "version 2" ?
From: Agustín K-ballo Bergé (kaballo86_at_[hidden])
Date: 2015-05-15 14:43:56

On 5/15/2015 12:09 PM, John Maddock wrote:
> Now that the release is out it's decision time:
>
> I'd like to merge the "Version2" branch of type_traits to develop, it
> passes all the tests, and I've been using it exclusively for testing and
> development locally for a few months now without issues.   But.... it's
> a big change with the potential to break a lot of folks stuff if things
> go wrong given that this is such a core component.  To recap the main
> advantages are:
>
> * Very nearly dependency free (other than Config), there's just
> comon_type which still has dependencies elsewhere - and even that
> disappears for a C++11 compiler.

I'm curious, `std::common_type` has accepted defects (LWG2141. 
common_type trait produces reference types; LWG2408. SFINAE-friendly 
common_type/iterator_traits is missing in C++14) as well as active ones 
(LWG2465. SFINAE-friendly common_type is nearly impossible to specialize 
correctly and regresses key functionality). Which semantics does 
`boost::common_type` v2 provide?

Regards,
-- 
Agustín K-ballo Bergé.-
http://talesofcpp.fusionfenix.com